The floating point control word is a register in the Intel 8087 FP coprocessor and in all later Intel/AMD/etc. processors that implement the 8087 instruction set.
That register contains bits that control various aspects of how the floating-point instructions must behave, e.g. rounding mode, precision and exception masks (also infinity type in coprocessors older than 80387).
For the later SSE/AVX instruction sets there is another register with similar control bits for the SSE/AVX instructions.
That register contains bits that control various aspects of how the floating-point instructions must behave, e.g. rounding mode, precision and exception masks (also infinity type in coprocessors older than 80387).
For the later SSE/AVX instruction sets there is another register with similar control bits for the SSE/AVX instructions.